JP2000001246A - Film roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the occurrence of creases in a rolled film during storage at a high temperature by forming a film roll to meet the condition that the circumferential length of the central part of a roll formed by winding a film round a take-up core with a width and a length equal to or larger than a specified value is larger than the average value of the circumferential lengths of both end parts of the roll. SOLUTION: A film roll is a roll formed by winding a film round a core with a width of 300 mm or more and with a length of 1000 m or more. When the circumferential length of the central part of the film roll is larger than the average value of the circumferential lengths of both end parts of the roll by 0.5 mm or more, a more remarkable effect can be obtained, and preferably 2.0 mm or more. Accordingly, it is comparatively convenient that the thickness in the cross direction in manufacturing the film is adjusted and in the width of the final film roll, the thickness of both end parts is made smaller than the thickness of the central part. To be concrete, in forming a film by fusion and extrusion through a slit die, the gap of the slit die is adjusted in the cross direction and adjusted so that the thickness of the film satisfies the described relationship at a desired width.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film roll formed by winding a thin film. More specifically, in a roll formed by winding a film around a winding core, air is evacuated between film layers under high-temperature storage by increasing the circumferential length at the center from the average value of the circumferential lengths at both ends of the roll. The present invention relates to a film roll capable of preventing "wrinkles" generated by the film roll.

[0002]

2. Description of the Related Art Films having a relatively small film thickness, especially 20
In the case of a film roll having a thickness of not more than μm, “wrinkles” which occur over time after winding are apt to occur. In order to prevent such "wrinkles" from occurring, it is known to reduce the air layer between the film layers during film winding (for example, JP-A-57-193322).

In order to prevent the transfer of the irregularities of the winding core to the film surface, it is known to form regular irregularities on the winding core (for example, see Japanese Unexamined Patent Publication No. Sho 62-2).
No. 22976). However, film rolls may be subjected to storage or heat treatment at high temperatures in the product distribution process or film processing process, and there is no suggestion regarding `` wrinkles '' generated under high temperature environment, such The occurrence of "wrinkles" could not be avoided.

[0004]

The conventional film roll is intended to prevent wrinkles from occurring immediately after winding or over time. However, in the course of film distribution, the film is rolled and placed in various environments. In particular, the temperature in a warehouse, especially in summer, often reaches 50 ° C. or more. Further, as a pre-treatment of the film processing step, a heat treatment is performed on the raw film at a high temperature of 60 ° C. or more in a roll state in order to improve the thermal stability of the film.

[0005] When the film is stored at a high temperature in a roll state, the air between the film layers thermally expands and moves between the film layers. "Wrinkles" occur in the circumferential direction. When film processing is performed using a film raw material having such “wrinkles”, the film roll may not be able to be used in a later step. For example, when a wrinkled film roll is used as a base film for a magnetic recording medium where the flatness of the film is strictly required, uneven coating of the magnetic layer is caused in the process of manufacturing the magnetic tape, and the yield is remarkably reduced. In addition, when used as a film for a capacitor, there are various problems such as surface defects at wrinkles significantly deteriorating electrical characteristics.

As a method for preventing such "wrinkles", a resin film or the like which promotes air bleeding by defining the formation of surface protrusions on the film has been proposed. A resin film capable of satisfying both has not been developed yet.

An object of the present invention is to solve the above-mentioned problem and to provide a film roll in which "wrinkles" hardly occur even when the film wound up in a roll is stored at a high temperature.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
The film is wound on a winding core with a width of 300 mm or more and a length of 1000
This is achieved by forming a film roll that satisfies that the circumferential length at the center is larger than the average value of the circumferential lengths at both ends of the roll.

To adjust the circumferential length of the film roll,
A desired circumferential length can be achieved by appropriately adjusting a method of adjusting a thickness pattern in a film width direction in a film manufacturing process or a stretching ratio of a film stretching step, a stretching temperature, a heat treatment temperature, a heat treatment time, and the like, A desired circumferential length can also be achieved by adjusting the shape of the winding core.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The film roll in the present invention is intended for a roll having a width of 300 mm or more and a length of 1000 m or more. With a film roll having a width of less than 300 mm, the above-described "wrinkles" are less likely to occur because the flow path of the entrained air in the film winding step is short. On the other hand, in the case of a film roll having a length of less than 1000 m, there is relatively little air between the film layers.
Is unlikely to occur. However, in the case of a film roll having a film width of more than 6000 mm, the effect of the present invention is hardly exhibited because the flow path of the entrained air becomes long. In a film roll having a film length exceeding 100000 m,
Since the number of laminated films increases, the film roll may be deformed due to accumulation of the distribution of the air between the film layers in the width direction.

In the present invention, the circumferential length at the center of the film roll must be larger than the average value of the circumferential lengths at both ends of the roll, and is preferably larger than any of the both ends. If the circumferential length of the central portion of the film roll satisfies this range, the effect of the present invention can be obtained, but the circumferential length of the central portion of the film roll is larger than the average value of the circumferential lengths at both ends of the roll. If it is 0.5 mm or more, a more remarkable effect is obtained, and more preferably 2.0 mm or more.
The method for setting the circumferential length of the film roll to such a range is not particularly limited, but the thickness in the width direction at the time of manufacturing the film is adjusted, and the thickness at both ends in the final width of the film roll is the thickness at the center. It is relatively simple to make it smaller. Specifically, when forming a film by melt-extrusion through a slit die, the gap between the slit dies is adjusted in the width direction so that the film thickness at a desired width satisfies the above-described relationship. A method of winding a film roll using a core having a larger diameter at the center portion than at both end portions may also be used.

The film thickness of the present invention is preferably 10 μm or less, more preferably 8 μm or less. When the magnetic tape is beyond the above range, it is not preferable to use a magnetic tape because the length of the tape that can be stored in a predetermined cassette is reduced, and the recording time and the recording capacity are reduced.

The film of the present invention preferably has a three-dimensional surface roughness (SRa) of at least one side of 0.01 μm or less, more preferably 0.008 μm or less.
m or less. Within such a range, the unevenness of the film surface will not be increased, and the electromagnetic conversion characteristics will not be deteriorated even in a base film for a magnetic recording medium in which the flatness of the film is strictly required.

The three-dimensional surface ten-point roughness (SRz) of at least one surface of the film of the present invention is preferably 0.20 μm or less, more preferably 0.15 μm or less. If the thickness exceeds the above range, when a magnetic tape is used, large projections on the support film may form projections on the surface of the magnetic tape, causing dropout of signals (dropout) and deterioration of electromagnetic conversion characteristics due to spacing loss. is there.

The film may be a laminated film, and the laminating method is not particularly limited, but a method of coextruding a molten resin to obtain a laminated film is generally used. The number of layers may be a multilayer structure of at least two or more layers.
The base film for a magnetic recording medium is preferably provided with a flat surface and a smooth surface by changing the surface configuration of the front and back surfaces so that high-speed winding with a slitter can be improved.

The wound core in the present invention preferably has a surface roughness (Ra) of 0.5 μm or less, more preferably 0.2 μm or less. If the thickness exceeds this range, the unevenness of the surface of the winding core is transferred to the surface of the film to be wound, so that as a base film for a magnetic recording medium in which the flatness of the film is strictly required, the electromagnetic conversion characteristics are significantly deteriorated. Sometimes. A method for adjusting the surface roughness (Ra) of the winding core to the above range is as follows.
Although not particularly limited, a desired surface roughness can be obtained by using a hard resin such as an epoxy resin on the core surface and grinding the surface with high precision. In particular, when a buff polishing step is performed after the grinding, the finishing can be performed more accurately.

The axial elastic modulus (Ya) of the winding core is preferably at least 1,000 kg / mm ² , more preferably at least 1500 kg / mm ² . If a winding core less than the above range is used, the winding core may be deformed by the tension and contact pressure applied when winding the film. The circumferential elastic modulus (Yr) of the winding core is also 100.
It is preferably at least 0 kg / mm ² , more preferably at least 1500 kg / mm ² . If a winding core less than the above range is used, the winding core may be deformed as described above. The method for setting the strength of the take-up core to such a range is not particularly limited.For example, in the case of a fiber-reinforced plastic core, it can be adjusted by appropriately selecting the amount of carbon fibers in the base material, and The desired strength can also be obtained by adjusting the thickness.

The base material of the winding core in the present invention is not particularly limited, but it is preferable to use a high-strength material such as fiber-reinforced plastic, aluminum and iron. In particular, a core made of a fiber-reinforced plastic is lightweight, which is effective in handling.

In the film roll of the present invention,
The resin constituting the film is not particularly limited, and specific examples thereof include a polyester resin, a polyamide resin, a polyolefin resin, and a polyphenylene sulfide resin. Polyester, particularly, ethylene terephthalate, ethylene α, β-bis ( 2-chlorophenoxy) ethane-4,4'-dicarboxylate, ethylene 2,6-naphthalate unit and at least one polyester resin having a main structural unit and polyamide, especially para-oriented aromatic polyamide. In the case of a polyamide resin as a main component, the effect of preventing "wrinkles" in the film roll of the present invention becomes remarkable, and thus it is desirable.
Note that two or more resins may be mixed for the purpose of increasing the strength or a copolymer may be used within a range not to impair the object of the present invention.

Further, in order to improve the handleability of the film, it is common to add inert particles as a lubricant, and the inert particles include colloidal silica, calcium carbonate, titanium dioxide, alumina, aluminum silicate, Particles such as cross-linked polystyrene and silicone are used.

The incorporation of the inert particles into the resin may be carried out at any stage before the melt extrusion step, for example, before, during or after the polymerization of the resin polymer. Also, it may be during the preparation step for melt extrusion.
In addition, as a method of incorporating the particles into the resin, for example, in the case of incorporating the particles into a polyester, a method of dispersing the particles in the form of a slurry in ethylene glycol, which is a diol component, and polymerizing the ethylene glycol with a predetermined dicarboxylic acid component Is preferred. When the particles are added, for example, if the water sol or alcohol sol obtained during the synthesis of the particles is added without drying, the dispersibility of the particles is very good, and the electromagnetic conversion characteristics can be improved. It is also effective to directly mix a water slurry of particles with predetermined polyester pellets, supply the mixture to a vent-type twin-screw extruder, and knead the polyester. As a method of adjusting the content of particles, it is effective to prepare a high-concentration particle master by the above method and dilute it with a polyester substantially free of particles at the time of film formation to adjust the content of particles. It is.

In the film of the present invention, a different polymer may be blended for the purpose of increasing the strength or the like, as long as the object of the present invention is not impaired, or an antioxidant, a heat stabilizer, an ultraviolet ray Organic additives such as an absorbent, a light-shielding agent, and an antistatic agent may be added to the extent that they are usually added.

Next, a method for obtaining the film roll of the present invention will be described. There are a center wind method and a surface wind method as a method of winding the film into a roll as described above. To obtain the roll of the present invention, either method may be selected. The surface wind method in which the pressure can be controlled is more preferable. The winding conditions are not particularly limited, but the following conditions are generally used. That is, the winding tension is 8 to 12 kg /
m, winding contact pressure 30-60 kg / m, winding speed 100-200 m
/ Min is preferable in terms of the appearance of the film roll. In particular, when winding a film having a width of 1 m and a length of 10,000 m, a winding tension of 10 to 12 kg / m and a winding contact pressure of 40 to 60 kg.
/ m and a winding speed of 130 to 180 m / min are preferable in terms of preventing wrinkles that occur over time.

[0024]

[Examples] [Measurement method of physical properties and evaluation method of effect] (1) Film surface roughness (SRa and SRz) Three-dimensional fine shape measuring instrument (model ET-30H) of Kosaka Laboratory
K) and a three-dimensional surface roughness analysis system (model MARM)
EC-3D) was used to measure the three-dimensional surface roughness (center plane average roughness and ten point average roughness). The conditions were as follows, and the value was an average value of 20 measurements.・ Tip tip radius: 0.5 μm ・ Load of the stylus: 4 mg ・ Vertical magnification: 50,000 times ・ Horizontal magnification: 100 times ・ Cutoff: 0.25 mm ・ Feed pitch: 10 μm ・ Measuring length: 20 mm ・ Measuring area : 0.8 mm ² · Measuring speed: 20 µm / sec (2) Circumferential length of film roll 0.1 mm at an arbitrary measuring position in the film width direction
The circumference of the measuring roll was measured using a band scale (JIS class 1) having the following accuracy.

(3) Film thickness Ten test pieces are taken about 100 mm in the longitudinal width direction of the film and over the entire width in the width direction.
0 places outside micrometer (JIS B7502)
And the value obtained by dividing the value by the number of films 10 was defined as the film thickness.

(4) Surface Roughness (Ra) of Winding Core According to JIS B0601, a surface roughness meter Surfcom 111A of Tokyo Seimitsu Co., Ltd.
The center line average roughness was measured at three points at 5 mm, and the average value was defined as the surface roughness.

(5) Axial elastic modulus (Ya) of the winding core: outer diameter 167 mm, inner diameter 152.5 mm, length 1200 m
The core of m was supported so that the fulcrum distance was 900 mm, a load was applied to the center of the core, and the axial elastic modulus was determined from the load-deflection ratio.

(6) Circumferential Elastic Modulus (Yr) of Winding Core A core having an outer diameter of 167 mm, an inner diameter of 152.5 mm and a length of 50 mm is placed between two flat plates, and a load is applied to the center. The circumferential elastic modulus was determined from the deflection ratio.

(7) Evaluation of "Wrinkles" by Preservation at High Temperature After leaving the film roll at 70 ° C. and 65% humidity for 3 days, the film roll is transported under the condition of 25 ° C. and 65% humidity.
After being left for 6 hours, the film is unwound from the film roll, and a free tension (in a state where the film hangs in the vertical direction by its own weight) and an optional tension are added.
The presence or absence of "wrinkles" due to temperature changes was confirmed. The "wrinkles" were all visually confirmed. The determination of "wrinkles" was performed by the following method. ◎: Free tension without wrinkles ○: Free tension with wrinkles and disappearing at 1 kg / m tension △: Free tension with wrinkles and disappearing at 3 kg / m tension × : Wrinkles with free tension that do not disappear even with a tension of 3 kg / m.

Example 1 Crosslinked divinylbenzene / styrene copolymer particles having an average particle diameter of 0.3 μm and 0.8 μm were used as additives.
Polyethylene terephthalate A containing 5% and 0.01% by weight was prepared. Further, polyethylene terephthalate B containing 0.1% by weight of crosslinked divinylbenzene / styrene copolymer particles having an average particle diameter of 0.3 μm was prepared as an additive. Each was supplied to two extruders, melt-extruded at 280 ° C., filtered with high precision, and then merged and laminated with a short-form merging block for two layers to form two-layer lamination. Then, it was wound around a casting roll having a surface temperature of 25 ° C. on a cooling roll through a slit die by using an electrostatic application casting method, and was cooled and solidified to obtain an unstretched laminated film. The unstretched laminated film is stretched 3.4 times in the longitudinal direction at 122 ° C., and the uniaxially stretched film is stretched 3.6 times in the width direction at a temperature of 100 ° C. using a tenter. After stretching 1.6 times at 205 ° C. under constant length
3 seconds, the film thickness is 6 μm, one film surface roughness (SRa) is 0.007 μm, film ten-point roughness (SRz) is 0.127 μm, and the other film surface roughness (SRa) is An original film of 0.013 μm was obtained. When obtaining this raw material, the film thickness is measured online in the width direction, and the data is fed back to the slit die to adjust the slit gap of the slit die corresponding to the slit width end in the slitter. The film thickness at the center was adjusted to be larger than the film thickness at the slit end. FIG.
When winding a film roll while cutting from a film raw material width of 2 to a slit width of 3, set a target value of the thickness pattern in the film raw material width direction as 1 when forming the film raw material, It is a conceptual diagram of the method of adjusting a film thickness.

This film is wound on a fiber reinforced plastic (FWP) core A (FWP-10 manufactured by Tenryu Kogyo Co., Ltd.) using a surface center wind type slitter into a film roll having a width of 1 m and a length of 10,000 m. The film was wound at a tension of 10 kg / m, a winding contact pressure of 50 kg / m, and a winding speed of 150 m / min.

Example 2 A raw material obtained under the same conditions as in Example 1 was ground by grinding the above-mentioned FWP core A, except that the slit gap of the slit die was adjusted so that the film thickness in the width direction was all the same. ,
FW with the diameter at both ends 0.2 mm smaller than the diameter at the center
Using the P core B, slitting was performed under the same conditions as in Example 1, and the film roll was wound up. FIG. 2 shows an FWP obtained by grinding a portion 3 from a cylindrical FWP core A and processing the core 2 so that the diameter at the end of the core 2 is smaller than the diameter at the center of the core 1.
FIG. 3 is a sectional view of a core B.

Example 3 An aromatic polyamide solution polymerized from N-methylpyrrolidone, 2-chloroparaphenylenediamine, 4,4'-diaminodiphenyl ether and terephthalic acid chloride was placed on a metal drum whose surface was polished from a slit die.
The mixture was uniformly cast at a temperature of 150 ° C., and dried under an atmosphere of 150 ° C. for 5 minutes. This film was peeled off from the belt and continuously immersed in a water bath at 20 ° C. for about 10 minutes to extract the solvent and the inorganic salt and stretched 1.05 times in the longitudinal direction. Further, the film was introduced into a tenter and stretched 1.1 times in the width direction at 300 ° C. to have a thickness of 4 μm and a surface roughness (SRa) of one film of 0.1.
003 μm, film surface ten-point roughness (SRz) is 0.0
An original film of 73 μm was obtained. When obtaining this film, the film thickness was adjusted in the same manner as in Example 1.
Using a FWP core A and a surface center wind type slitter, this film roll is wound on a film roll having a width of 1 m and a length of 5,000 m with a winding tension of 7 kg / m, a winding contact pressure of 30 kg / m, and a winding. A wound film roll was obtained at a speed of 70 m / min.

Comparative Example 1 The winding core used in Example 2 was FWP core A
A film roll was obtained under the same conditions except for the above.

Comparative Example 2 A film roll was obtained under the same conditions as in Example 1 except that the winding core was changed to a paper core (MA core manufactured by Showa Marutsu Co., Ltd.). Was.

Comparative Example 3 When the film roll of Example 1 was obtained, the wound core was a polyvinyl chloride (PVC) core (manufactured by Showa Marutsu Co., Ltd.).
A film roll was obtained under the same conditions as in Example 1 except that the film roll was changed to.

Table 1 summarizes the physical properties of the film and the winding core, the circumferential lengths at both ends and the center of the film roll, and the occurrence of "wrinkles" due to high-temperature storage.

As shown in Table 1, the film rolls of Examples 1 to 3 satisfying the requirements of the present invention have no "wrinkles" after storage at a high temperature, and have no convexly deformed portions on the film surface. On the other hand, the film rolls of Comparative Examples 1 to 3 do not satisfy the requirements of the present invention, but "wrinkles" occurred after storage at high temperatures.

[0039]

[Table 1]

[0040]

The film roll of the present invention, while being a conventional thin and smooth film, can avoid environmental changes, especially "wrinkles" caused by thermal expansion of air between film layers under high temperature storage. The target value is high.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a thickness pattern in a width direction of an original film of the present invention.

FIG. 2 is a cross-sectional view in the width direction of the FWP core B of the present invention.

[Explanation of symbols]

 1: Thickness pattern 2: Raw film width 3: Slit width 4: Center diameter 5: End diameter 6: Ground part

Claims (11)

[Claims] A film having a width of at least 300 mm on a winding core;
In the roll which winds up 1000m or more in length,
A film roll characterized in that the circumference at the center is larger than the average value of the circumference at both ends of the roll. 2. The film roll according to claim 1, wherein the film thickness is 10 μm or less. 3. The film roll according to claim 1, wherein the three-dimensional surface roughness (SRa) of at least one surface of the film is 0.01 μm or less. 4. The film roll according to claim 1, wherein the three-dimensional surface ten-point average roughness (SRz) of at least one side of the film is 0.20 μm or less. 5. The film is a laminated film having at least one surface having a three-dimensional surface roughness (SRa) of 0.008 μm.
m and three-dimensional surface ten-point average roughness (SRz)
The film roll according to any one of claims 1 to 4, wherein the thickness of the film roll is 0.15 µm or less. 6. The film roll according to claim 1, wherein the surface roughness (Ra) of the take-up core is 0.5 μm or less. 7. An axial elastic modulus (Ya) of the winding core is 100.
0 kg / mm ² or more in a film roll according to any one of claims 1 to 6 is. 8. The circumferential elastic modulus (Yr) of the winding core is 10
00 kg / mm ² or more in a film roll according to any one of claims 1 to 7. 9. The film roll according to claim 1, wherein the winding core is a core based on a fiber-reinforced plastic. 10. The film roll according to claim 1, wherein the film is made of a polyester resin as a base material.
A film roll according to the item. 11. The film roll according to claim 1, wherein the film is made of a polyamide resin as a base material.